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Superinfections

One reason to avoid taking unnecessary antibiotics is that antibiotic treatment puts you at risk for additional infections - so called superinfections.

Such infections are unrelated to the first infection for which the antibiotic was originally taken. Instead it is the antibiotic treatment that makes the second infection possible because it disturbs the normal bacterial flora in the body. Imbalance in the normal flora can last for several months, even up to several years following treatment (reviewed in).

When the normal flora is reduced, it provides an opportunity for pathogenic microbes to grow and potentially cause a new infection. The microbes can come from a person’s own flora or from the outside environment. The risk for superinfections is higher when using broad-spectrum antibiotics, as compared to narrow-spectrum antibiotics affecting a smaller number of bacteria. Further, long duration of antibiotic treatment, immunosuppression and poor health status of the patient increase the risk. Superinfections range from mild infections that do not need further treatment to very severe infections that can lead to death

Diseases associated with antibiotic use, examples:

Clostridium difficile can cause severe, even deadly, diarrhea. As an example, it is one of the most common hospital acquired infections in the US, where around 250,000 patients get infected every year, and 14,000 patients die. Clostridium difficile infection is strongly associated with antibiotic treatment, especially antibiotics that kills many different types of bacteria (for example fluoroquinolones and extended-spectrum cephalosporins). Also, C. difficile can be resistant to antibiotics commonly used in health care settings. This allows the bacteria to thrive in health care facilities where antibiotic usage is high.

A common complication following antibiotic treatment is a fungal infection, for example, oral or vaginal thrush caused by different types of the fungal yeast Candida. Yeast can often be found in small numbers in and on the body, but antibiotic treatment disturbs the balance between different microbes and paves the way for the yeast to increase in numbers. In some cases, fungal infections can spread to the blood and be very severe.

Several studies have found a link between antibiotic use and increased risk of urinary tract infections. For example, women treated with antibiotics were 2 to 5 times more likely to contract a urinary tract infection than untreated women.

Preliminary studies of the effects of antibiotics on the human microbiome link several severe diseases/conditions to antibiotic exposure at different stages in life, including obesity.

This film and the accompanying article describe the case of a young woman who became ill from Clostridium difficile after being treated with antibiotics for a dangerous antibiotic-resistant MRSA infection. It further describes what is at stake when getting C. difficile and the use of an experimental new method to treat it: Fecal transplants.

The majority of the cases of C. difficile infection develop in patients taking antibiotics. Learn more about C. difficile infections in this material developed by the Centers for Disease Control and Prevention (CDC).